Amplifier



H. M. JOHNSON AMPLIFIER Filed Nov. 13. 1924 Oct. 4 1927.

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UNITED STATES PATENT oEFic.

HARLY JOHNSON, F RIVERiROUGE, MICHIGAN.

AMPLIFIER.

Application ea November 13, 1224. Serial No. 749,724.

My invention relates to improvements in amplifiers.

It is an object of the invention to provide an amplier into which thesound waves enter through two downwardly inclined diverging passageshaving the lower ends of their adjacent sidesconnected by means of awall substantially parallel with the ampli* fier base, and having thelower end of their outer sides flared inwardly, as it is found that bythis construction that a full even tone is obtained. The uniformincrease in the cross sectional area insures even ampli.-

fication, and the opposing sound waves dew flected in two directionsresult in a purity of tone.

Another object of the invention is to provide an amplier consisting inpart of an eddying or equalizing chamber not directly in line with theow of the sound waves by means of which blasting can be almost entirelyeliminated.

A further object of the invention is to provide Van amplifier soconstructed that when applied to phonographs, and particularly tovportable types, considerable space can be saved on account of the factthat the motor may be placed within the amplifier without in any wayaffecting the volume or quality of the sound.

Vith these and other objects in view, which will be pointed out as thedescription proceeds, the invention consists in certain novelconstruction and combination of parts hereinafter more fully describedwith the aid of the accompanying drawings.

Figure 1 illustrates a front elevation of a portable phonograph with themotor arranged inside the amplifier.

Figure 2 is a side elevation.

Figure 3 is a plan view.

Figure 4 shows a plan with the top of the amplifier removed, and

Figure 5 is a detail.

In the drawings the amplifier 1 is shown within a portable phonograph, 2indicating the casing of the latter and 3 the lid.

The upper wall of the amplifier consists of a main portion 4; onto theunderside of which the motor 5 is attached as by screws 30, and aportion 6 which carries the tone arm support 7. The latter portion 6 ispartly supported by a diagonal strip 22 glued to the underside of themain portion 4. The connector 8 which extends downwardly from within thesupport 7, connects thelatter with the throat 9, from which extenddownwardly the inclined divergi-ng passages 10 and 11, the adjacentsides 12 and 13 of which have the transverse wall 141 secured to theirlower edges. The wall 141 is sub stantially parallel with the base 15 ofthe amplifier.

The lower outer edges 1G and 17 of the passages 10 and 11 project below,and are curved inwards towards, the transverse wall 14.' rlhe soundwaves are discharged through outlets 19 in the frontpanel 18 of theamplifier.

In the construction shown in the drawing, wherein one inclined passageis at right angles to the front panel 18,1 utilize a curved wall 20 tofurther aid in throwing the sound waves forward. y

The amplifier is preferably located partly above and partly below thejoint between the casing 2 and the lid 8. vThe reason for favoring thisarrangement isV in order' to facilitate the installation of an upwardlyIcurved front portion 21 of the b-ase 15, which projects forwardlybeyond the front 18. This upwardly curved port-ion, the top of whichterminates below the top of the front 18, is of assistance in completelyblending the sound waves particularly in the case of small sizedmachines'. 24 is an opening through the side of the amplifier throughwhich vthe winding spindle 23 extends.

rThe base 15 is securely fastened on the sides, front, and yrear of thecasing 2 in which it is contained, but has nothing in direct contactwith it intermediately of its length or width. The front 18 and thercurved wall 2O terminate at their lower edges just above and out ofcontact with the said base.

25 designates the upper portion of the am-V plifier, which constitutesan equalizing or eddying chamber by which sudden extremes of sound aremodified, and blasting almost entirely eliminated, the large' volume ofthe space therein having a tendency to retard. the outward flow ofsudden outbursts of sound. p

The downwardly inclined diverging paslos sages 10 and 11 are preferablymade of very thin material such as heavy bristol board treated on bothsides with shellac, and the Vtransverse wall 14 is generally fastened tothe adjacent sides 10 andll by rivets 26,

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which pass through one of the said walls and also through lugs 27integral with the transverse wall 14.

In the foregoing the invention has been described and shown as appliedto a portable phonograph. It is obvious however that it can with veryslight modifications be applied to a large cabinet phonograph whereinthe tone arm support is located substantially centrally and towards theback of the niachine. In that case the downwardly inclined diverging4passages would stillV be are ranged one on each side of the motor.

Again the invention maybe used for othei` purposes, independently ofphonographs, such as radio amplification.

And while in the foregoing the preferred embodiment of the invention hasbeen described and shown, it is understood thatv the construction hereindescribed is susceptible to alterations and modifications provided thesaid alterations and modifications fall within thescope of what I claim.

What I claim is:

1. In a sound amplifier, the combination of a throat member, downwardlyinclined diverging passages open on their undersides dependinglyconnected to said throat member, a transverse wall supported by theinner adjacent sides of said diverging passages towards their lowerends, said transverse wall forming the top of a lower chamber' intowhich both of said passages discharge, and a front having sounddischarge openings.

2. In a sound amplifier as described in claim l, the combination whereinthe sound discharge openings extend above and below the transverse wall.y

3. In a sound amplifier as described in claim 1, the combination whereinthe outer sides of the inclined passages extend below the transversewall and are curved inwardly at their lower ends.

1. In a sound amplifier as described in claim 1, the combination whereinthe transverse wall is spaced from the sides of the amplifier so thatcommunication is aii'orded between said lower chamber and an upperchamber the underside of' which latter is bounded by said transversewall.

5. In a device of the character described, the combination of soundamplifier having a throat member mounted thereon, downwardly inclineddiverging passages open on their undersides dependingly connected tosaid throat member, a transverse wall supported by the inner adjacentsides of said dii/'erging passages towards their lower` ends, saidtransverse wall forming the top of a lower chamber' into which both ofsaid passages discharge, a front having discharge openings therethrough,a motor dependingly arranged in said sound amplifier, said motorterminating above said transverse wall, and a spindle driven by andforming part of' said motor extending through the top of said soundamplifier.

HARLEY M. .ior-mson.

